Polysilsesquioxanes (POSS) is a novel organic-inorganic nanoparticle that was first synthesized in 1946 by D. W. et al. The molecular formula of POSS is (RSiO1.5)n(4≤n≤8), wherein R is an substituent, and may be an inert group such as H, alkyl group and aryl group, or an active group such as a vinyl group or an amino group. POSS has an inorganic skeleton and the molecular dimensions are in range of 1-3 nm. POSS has a nano-scale cubic three-dimensional structure cavity, and there are 8 modifiable sites at each of the eight Si-sites. The reactive groups can be chemically modified to react with the polymer or polymer monomer, thus having a huge potential for modification.
The acrylic polymer can form complex with chromium salt, and is a polymer tanning agent with strong bonding ability and good filling effect. This kind of tanning agent can improve the physical mechanical properties of leather, and play absorption and fixation effect to chromium ions. Compared with linear polymer, the 8 vertices of the POSS combined with acrylic polymer to form a unique multi-side chain structure, which greatly increases the number of active groups of the polymer side chain. At the same time, octavinyl silsesquioxane is copolymerized with the acrylic monomer to form a nano-hybrid material with covalent bonding between the organic-inorganic phase, and the nano-hybrid material forms nano and micro-scale combination with the leather collagen, which is expected to improve thermal stability and filling effect to leather collagen fibers. The hybrid polymer with multi-side chain can further improve the multi-point combination with the leather collagen, increase the absorption rate of chromium, reduce the pollution of tanning and achieve clean production.